MOCVD Growths of the InAs QD Structures for Mid-IR Emissions

In this research, InAs quantum dot structures for mid-infrared emission were self-assembled on InP substrate by using metal-organic chemical vapor deposition. To improve the grown quantum dot’s shape, the dot density and the dot size uniformity, a two-step growth method has been used and investigated. By changing the composition of the InxGa1 – xAs matrix layer of the InAs / InxGa1 – xAs / InP quantum dot structure, emission wavelength of the InAs quantum dot structure has been extended to the longest 2.35 m measured at 77 K. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3538

Surface enhanced Raman scattering of Ag or Au nanoparticle-decorated reduced graphene oxide for detection of aromatic molecules

We report a method for fabrication of an efficient surface enhanced Raman scattering (SERS) substrate by combination of metallic nanostructures and graphene, which shows dramatic Raman enhancement and efficient adsorption of aromatic molecules. As an example, the fabricated Ag or Au nanoparticle (NP)-decorated reduced graphene oxide (rGO) on Si substrate is used as an efficient SERS substrate to detect the adsorbed aromatic molecules with a low detection limit at nM level. Systematic studies on the effects of NP size and substrate morphology on Raman enhancement are presented. This method might be useful for the future application in detection of biomolecules, such as DNA and protein

Enhanced transport in transistor by tuning transition-metal oxide electronic states interfaced with diamond

High electron affinity transition-metal oxides (TMOs) have gained a central role in two-dimensional (2D) electronics by enabling unprecedented surface charge doping efficiency in numerous exotic 2D solid-state semiconductors. Among them, diamond-based 2D electronics are entering a new era by using TMOs as surface acceptors instead of previous molecular-like unstable acceptors. Similarly, surface-doped diamond with TMOs has recently yielded record sheet hole concentrations (2 × 1014 cm−2) and launched the quest for its implementation in microelectronic devices. Regrettably, field-effect transistor operation based on this surface doping has been so far disappointing due to fundamental material obstacles such as (i) carrier scattering induced by nonhomogeneous morphology of TMO surface acceptor layer, (ii) stoichiometry changes caused by typical transistor fabrication process, and (iii) carrier transport loss due to electronic band energy misalignment. This work proposes and demonstrates a general strategy that synergistically surmounts these three barriers by developing an atomic layer deposition of a hydrogenated MoO3 layer as a novel efficient surface charge acceptor for transistors. It shows high surface uniformity, enhanced immunity to harsh fabrication conditions, and benefits from tunable electronic gap states for improving carrier transfer at interfaces. These breakthroughs permit crucial integration of TMO surface doping into transistor fabrication flows and allow outperforming electronic devices to be reached

Mesoporous ZnAl2Si10O24 nanofertilizers enable high yield of Oryza sativa L.

Controllable release of nutrients in soil can overcome the environmental problems associated with conventional fertilizer. Here we synthesized mesoporous nanocomposite of Zinc aluminosilicate (ZnAl2Si10O24) via co-precipitation method. Oryza sativa L. husk was used as source of silica for making the synthesis process green and economical. The nanocomposite was subsequently loaded with urea to achieve the demand of simultaneous and slow delivery of both zinc and urea. The structural characterization of nanocomposite was done by FTIR, XRD, TGA, BET, SEM/EDX and TEM. The release of urea and zinc was investigated with UV-Vis spectrophotometry and atomic absorption spectroscopy, respectively, up to 14 days. It was noted that urea holding capacity of mesoporous ZnAl2Si10O24 nanocomposite over long period of time was increased as compared to bulk aluminosilicates, due to its high surface area (193.07 m2 g-1) and small particle size of (64 nm). Urea release was found highest in first 24 h because of excess of adsorption on nanocomposite and least at 14th day. Fertilizer efficiency was checked on Oryza sativa L. in comparison with commercial urea and results showed significantly higher yield in case of urea loaded ZnAl2Si10O24 nanocompositeTe authors are thankful to Ofce of Research Innovation and Commercialization, GC University Lahore for providing Research Support for this research work though Grant No. 160/ORIC/16. Te author (M. A Farrukh, Principal Investigator) is much grateful to Higher Education Commission, Islamabad (No. 20-3142/NRPU/R&D/ HEC/14, No. 20-2660/NRPU/R&D/HEC/13) and Te World Academy of Sciences (11-028 RG/MSN/AS_C) for providing sufcient funds to purchase basic equipment for establishing the Nano-Chemistry Lab

The data-intensive scientific revolution occurring where two-dimensional materials meet machine learning

Machine learning (ML) has experienced rapid development in recent years and been widely applied to assist studies in various research areas. Two-dimensional (2D) materials, due to their unique chemical and physical properties, have been receiving increasing attention since the isolation of graphene. The combination of ML and 2D materials science has significantly accelerated the development of new functional 2D materials, and a timely review may inspire further ML-assisted 2D materials development. In this review, we provide a horizontal and vertical summary of the recent advances at the intersection of the fields of ML and 2D materials, discussing ML-assisted 2D materials preparation (design, discovery, and synthesis of 2D materials), atomistic structure analysis (structure identification and formation mechanism), and properties prediction (electronic properties, thermodynamic properties, mechanical properties, and other properties) and revealing their connections. Finally, we highlight current research challenges and provide insight into future research opportunities.This work was supported by the ANU Futures Scheme (Q4601024), the Australian Research Council (DP190100295, LE190100014), the National Natural Science Foundation of China (No. 51706114 and 51302166), Functional Materials Interfaces Genome (FIG) project, and Doctoral Fund of Ministry of Education of China (20133108120021)

Extraordinary second harmonic generation modulated by divergent strain field in pressurized monolayer domes

The most prominent form of nonlinear optical (NLO) frequency conversion is second harmonic generation (SHG), where incident light interacts with a nonlinear medium producing photons at double the input frequency, which has vast applications in material and biomedical science. Emerging two-dimensional nonlinear optical materials led by transition metal dichalcogenides (TMDs) have fascinating optical and mechanical properties and are highly anticipated to overcome the technical limitations imposed by traditional bulky NLO materials. However, the atomic scale interaction length and low conversion efficiency in TMD materials prevent their further implementation in NLO applications. While some uniaxial strain-engineering studies intensively investigated the anisotropic SHG response in TMDs, they did not realize giant SHG enhancement by exploiting the opto-mechanical characteristics. Herein, we employ proton (H+) irradiation to successfully fabricate large pressurized monolayer TMD domes (d ≥ 10 μm) and conduct a comprehensive investigation and characterization of their SHG performance enhancement. We show that the intensity of SHG is effectively enhanced by around two orders of magnitude at room temperature. Such giant enhancement arises from the distinct separation distance induced by capped pressurized gas and the hemi-spherical morphology, enabling constructive optical interference. Moreover, the unique divergent strain field in TMD domes promotes the first experimental study on the anisotropic nonlinear optical behavior based on biaxial strain conditions in terms of varying strain orientation and relative weights. Our work demonstrates a promising system with enhanced NLO performance and well-preserved biocompatibility, paving a way toward the future nano-scaled quantum optics design and biomedical applications

Plasmonically enhanced photoluminescence of monolayer MoS2 via nanosphere lithography-templated gold metasurfaces

We demonstrate a simple, cost-effective method to enhance the photoluminescence intensity of monolayer MoS2. A hexagonal symmetric Au metasurface, made by polystyrene nanosphere lithography and metal coating, is developed to enhance the photoluminescence intensity of monolayer MoS2. By using nanospheres of different sizes, the localized surface plasmon resonances of the Au metasurfaces can be effectively tuned. By transferring monolayer MoS2 onto the Au metasurface, the photoluminescence signal of the monolayer MoS2 can be significantly enhanced up to 12-fold over a square-centimeter area. The simple, large-area, cost-effective fabrication technique could pave a new way for plasmon-enhanced light-mater interactions of atomically thin two-dimensional materials.This work was supported in part by National Natural Science Foundation of China (Grant No. 62075093 and 61805113), China Postdoctoral Science Foundation (2020M672697), Natural Science Foundation of Guangdong Province (Grant No. 2018A030310224 and 2019A1515110864), Guangdong Innovative and Entrepreneurial Research Team Program (Grant No. 2017ZT07C071), and Shenzhen Science and Technology Innovation Commission (Grant No. GJHZ201809281552 07206, JCYJ20170817111349280, and JCYJ2018030518063 5082). Meng Zhao acknowledges the support from the Agency for Science, Technology and Research (A*STAR) (Grant No. 152700014 and H19H6a0025)

Synergizing Phase and Cavity in CoMoOxSy Yolk-Shell Anodes to Co-Enhance Capacity and Rate Capability in Sodium Storage

Sodium‐ion batteries (SIBs) have been recognized as the promising alternatives to lithium‐ion batteries for large‐scale applications owing to their abundant sodium resource. Currently, one significant challenge for SIBs is to explore feasible anodes with high specific capacity and reversible pulverization‐free Na+ insertion/extraction. Herein, a facile co‐engineering on polymorph phases and cavity structures is developed based on CoMo‐glycerate by scalable solvothermal sulfidation. The optimized strategy enables the construction of CoMoOxSy with synergized partially sulfidized amorphous phase and yolk-shell confined cavity. When developed as anodes for SIBs, such CoMoOxSy electrodes deliver a high reversible capacity of 479.4 mA h g-1 at 200 mA g-1 after 100 cycles and a high rate capacity of 435.2 mA h g-1 even at 2000 mA g-1, demonstrating superior capacity and rate capability. These are attributed to the unique dual merits of the anodes, that is, the elastic bountiful reaction pathways favored by the sulfidation‐induced amorphous phase and the sodiation/desodiation accommodatable space benefits from the yolk-shell cavity. Such yolk-shell nano‐battery materials are merited with co‐tunable phases and structures, facile scalable fabrication, and excellent capacity and rate capability in sodium storage. This provides an opportunity to develop advanced practical electrochemical sodium storage in the future.This work was supported by the National Science Foundation of China (Grant No. 51402232), the Natural Science Basis Research Plan in Shaanxi Province of China (2018JM5085), the State Key Laboratory of Electrical Insulation and Power Equipment (No. EIPE19127), the Key Laboratory Construction Program of Xi’an Municipal Bureau of Science and Technology (201805056ZD7CG40), the ANU Futures Scheme (Q4601024) and the Australian Research Council (DP190100295, LE190100014), and China Scholarship Council (No. 201906280078) scholarship

Nonepitaxial Gold-Tipped ZnSe Hybrid Nanorods for Efficient Photocatalytic Hydrogen Production

For the first time, colloidal gold (Au)–ZnSe hybrid nanorods (NRs) with controlled size and location of Au domains are synthesized and used for hydrogen production by photocatalytic water splitting. Au tips are found to grow on the apices of ZnSe NRs nonepitaxially to form an interface with no preference of orientation between Au(111) and ZnSe(001). Density functional theory calculations reveal that the Au tips on ZnSe hybrid NRs gain enhanced adsorption of H compared to pristine Au, which favors the hydrogen evolution reaction. Photocatalytic tests reveal that the Au tips on ZnSe NRs effectively enhance the photocatalytic performance in hydrogen generation, in which the single Au-tipped ZnSe hybrid NRs show the highest photocatalytic hydrogen production rate of 437.8 µmol h−1 g−1 in comparison with a rate of 51.5 µmol h−1 g−1 for pristine ZnSe NRs. An apparent quantum efficiency of 1.3% for hydrogen evolution reaction for single Au-tipped ZnSe hybrid NRs is obtained, showing the potential application of this type of cadmium (Cd)-free metal–semiconductor hybrid nanoparticles (NPs) in solar hydrogen production. This work opens an avenue toward Cd-free hybrid NP-based photocatalysis for clean fuel production.W.C. and X.L. contributed equally to this work. This work was supported by the Australian Research Council (ARC) Discovery Early Career Researcher Award (DECRA) (DE 160100589) and discovery project (DP 170104264). Y.L. acknowledges support from the NSFC (grant no. 11674131). W.C. acknowledges the scholarship from the China Scholarship Council